The Clinical Epilepsy Section has begun to place more emphasis on the clinical pharmacology of new antiepileptic drugs, with somewhat diminished studies of commonly-used medical therapies. Pilot studies are now complete on felbamate (2-phenyl 1-1,3 propanedial dicarbamate). The two patients studied are continuing on a long-term follow-up protocol. Following completion of the pilot study, the randomized placebo-controlled double-blind study was initiated. The purpose of this study is to obtain definitive information regarding the efficacy of felbamate in patients with uncontrolled partial seizures. The unique three period crossover design allows unbiased estimates of drug effects even in the presence of a carry-over effect from one period to the next. A single patient has completed the study. The patient exhibited fewer seizures during the felbamate period and has continued on the medication as an outpatient. In a separate study of patients with partial seizures, a pilot effort will be undertaken to evaluate a very old compound, dapsone, for its effect on control of partial seizures. This anti-leprosy drug recently demonstrated efficacy in animal models --such as the maximal electroshock--and its protective index is promising. The study will evaluate the pharmacology of the drug in humans, identify drug interactions with current antiepileptic drugs, establish the maximum tolerated dose, and obtain preliminary assessment of efficacy of the drug. This study will be carried out in both inpatient and outpatient facilites, but with outpatient emphasis. Such will permit a longterm follow up of the possible usefulness of this drug in patients with partial seizures. Recent studies are complete in the evaluation of phenytoin phamacokinetics and of phenytoin protein plasma binding. In the latter study, the Section demonstrated that there is little clinical rationale for measuring free rather than total levels in most patients taking the medication. A study of carbamazepine and its metabolites is continuing; an understanding of the major metabolite, carbamazepine 10-11 epoxide, is sought.